Metastructure Engineering with Ruddlesden–Popper 2D Perovskites: Stability, Flexibility, and Quality Factor Trade-Offs

In this study, we investigate the opto-electro-mechanical properties, thermodynamic stability, and moisture stability of the Ruddlesden–Popper (RP) two-dimensional perovskites of L2PbI4 (L = PEA, FPEA, BA, and BZA) using density functional theory. The goal is to explore their potential application in metastructures. The results show that the stability of FPEA2PbI4 is better than that of PEA2PbI4, BA2PbI4, and BZA2PbI4 due to the replacement of a hydrogen atom with a fluorine atom. On the other hand, BA2PbI4 is more flexible than other materials because it lacks an aromatic ring in its spacer cation, but it is less stable. We introduce a new kind of metastructure composed of an RP perovskite film and conduct an extensive investigation of the quasi-bound states in the continuum (q-BIC) characteristics by near-field analysis and multipole decomposition calculations. The q-BIC resonances in BZA2PBI4 have a greater quality factor due to its larger refractive index in comparison to other materials. Therefore, based on these results, the perovskite materials can be selected for the metastructures from different aspects of stability, flexibility, and refractive index.